Apparatus and method for depositing thin film on wafer using atomic layer deposition

ABSTRACT

An atomic layer deposition (ALD) thin film deposition apparatus including a reactor  100  in which a wafer is mounted and a thin film is deposited on the wafer, a first reaction gas supply portion  210  for supplying a first reaction gas to the reactor  100,  a second reaction gas supply portion  230  for supplying a second reaction gas to the reactor  100,  a first reaction gas supply line  220  for connecting the first reaction gas supply portion  210  to the reactor  100,  a second reaction gas supply line  240  for connecting the second reaction gas supply portion  230  to the reactor  100,  a first inert gas supply line  260  for supplying an inert gas from an inert gas supply source  250  to the first reaction gas supply line  220,  a second inert gas supply line  270  for supplying an inert gas from the inert gas supply source  250  to the second reaction gas supply line  240,  and an exhaust line  400  for exhausting the gas within the rector  100  to the outside.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an atomic layer deposition (ALD)thin film deposition apparatus for depositing a thin film on asemiconductor, for example, on a semiconductor wafer, and a methodthereof.

[0003] 2. Description of the Related Art

[0004] A thin film deposition apparatus forms a predetermined thin filmon a wafer by supplying reaction gases to the wafer received within areactor. This thin film deposition apparatus includes a chemical vapordeposition (CVD) thin film deposition apparatus, an atomic layer epitaxy(ALE) thin film deposition apparatus, and others, and has been appliedto various fields for manufacturing semiconductor devices.

[0005] Thin film deposition apparatuses have been continuously improvedto make a highly-integrated chip and increase the efficiency ofmanagement and productivity.

SUMMARY OF THE INVENTION

[0006] An objective of the present invention is to provide an ALD thinfilm deposition apparatus and a method thereof, by which a thin filmhaving excellent electrical characteristics, a high purity, in whichimpurities are removed as much as possible, and an excellent stepcoverage can be formed, and the efficiency and productivity ofmanagement can be improved.

[0007] Another objective of the present invention is to provide an ALDthin film deposition apparatus including an exhaust line forcontinuously maintaining a desired process pressure before and afterdepositing a thin film, and pumping a reactor, and a deposition method.

[0008] To achieve the above objectives, the present invention providesan atomic layer deposition (ALD) thin film deposition apparatusincluding: a reactor 100 in which a wafer is mounted and a thin film isdeposited on the wafer; a first reaction gas supply portion 210 forsupplying a first reaction gas to the reactor 100; a second reaction gassupply portion 230 for supplying a second reaction gas to the reactor100; a first reaction gas supply line 220 for connecting the firstreaction gas supply portion 210 to the reactor 100; a second reactiongas supply line 240 for connecting the second reaction gas supplyportion 230 to the reactor 100; a first inert gas supply line 260 forsupplying an inert gas from an inert gas supply source 250 to the firstreaction gas supply line 220; a second inert gas supply line 270 forsupplying an inert gas from the inert gas supply source 250 to thesecond reaction gas supply line 240; and an exhaust line 400 forexhausting the gas within the rector 100 to the outside.

[0009] To achieve the above objectives, the present invention providesan ALD thin film deposition method using a thin film depositionapparatus including a reactor 100 in which a wafer is mounted and a thinfilm is deposited on the wafer, a first reaction gas supply portion 210for supplying a first reaction gas to the reactor 100, a first reactiongas supply line 220 for connecting the first reaction gas supply portion210 to the reactor 100, a second reaction gas supply portion 230 forsupplying a second reaction gas to the reactor 100, a second reactiongas supply line 240 for connecting the second reaction gas supplyportion 230 to the reactor 100, a first inert gas supply line 260 forsupplying an inert gas, the flow of which has been controlled, to thefirst reaction gas supply line 220, a second inert gas supply line 270for supplying an inert gas, the flow of which has been controlled, tothe second reaction gas supply line 240, and an exhaust line 400 forexhausting the gas within the rector 100 to the outside. In this method,a first reaction gas, the flow of which has been controlled, and theflow-controlled inert gas are mixed and supplied to the upper surface ofthe wafer within the reactor 100. Also, a second reaction gas, the flowof which has been controlled, and the flow-controlled inert gas aremixed and supplied to the edges of the wafer within the reactor 100.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The above objectives and advantages of the present invention willbecome more apparent by describing in detail preferred embodimentsthereof with reference to the attached drawings in which:

[0011]FIG. 1 is a schematic diagram of an atomic layer deposition (ALD)thin film deposition apparatus according to a first embodiment of thepresent invention;

[0012]FIG. 2 is an exploded perspective view of a reactor in the ALDthin film deposition apparatus of FIG. 1;

[0013]FIG. 3 is an exploded perspective view of a shower head plate anda diffusion plate in the reactor of FIG. 2;

[0014]FIG. 4 is a cross-sectional view of the reactor of FIG. 2;

[0015]FIG. 5 is a magnified cross-sectional view of the first mixingunit of the reactor of FIG. 4;

[0016]FIG. 6 is a graph showing the relationship between an interval (D)and a specific resistance while a thin film is deposited;

[0017]FIG. 7 shows a reactor combined with a transfer module through avat valve;

[0018]FIG. 8 is a cross-sectional view of an ALD thin film depositionapparatus according to a second embodiment of the present invention; and

[0019]FIG. 9 is a cross-sectional view of an ALD thin film depositionapparatus according to a third embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020]FIG. 1 shows an atomic layer deposition (ALD) thin film depositionapparatus that can deposit a TiN or TaN thin film on a wafer. Depositionof a TiN thin film will now be described as an example. In order to forma TiN thin film, TiCl₄ is used as a first reaction gas, NH₃ is used as asecond reaction gas, and Ar is used as an inert gas.

[0021] Referring to FIG. 1, an ALD thin film deposition apparatusincludes a reactor 100 for receiving a wafer and depositing a thin filmon the wafer, a gas jungle (this term was made by the present inventorto describe complicatedly-connected gas lines) for supplying a reactiongas to the reactor 100, and an exhaust line 400 for exhausting the gaswithin the reactor 100 to the outside.

[0022]FIG. 2 is an exploded perspective view of a reactor in the ALDthin film deposition apparatus of FIG. 1. FIG. 3 is an explodedperspective view of the reactor of FIG. 2, in which a shower head plateis separated from a diffusion plate. FIG. 4 is a cross-sectional view ofthe reactor of FIG. 2, and FIG. 5 is a magnified cross-sectional view ofthe first mixing unit of the reactor of FIG. 4.

[0023] Referring to FIGS. 2, 3, 4 and 5, the reactor 100 includes areactor block 110 on which a wafer is placed, a shower head plate 120coupled to the reactor block 110 using hinges 128 and 129, a diffusionplate 130 installed on the shower head plate 120 for spraying a reactiongas and/or inert gas, and a wafer block 140 installed within the reactorblock 110, on which a wafer is seated.

[0024] First and second connection lines 121 and 122 are installed onthe shower head plate 120, and are connected to first and secondconnection pipes 111 and 112 to be described later.

[0025] The first and second connection pipes 111 and 112 are installedon the reactor block 110, and connected to the first and secondconnection lines 121 and 122, respectively, via a connecting portion113. An O-ring 113 a is installed on the connecting portion 113, andconnects the first and second connection pipes 111 and 112 to the firstand second connection lines 121 and 122 so that they are sealed when theshower head plate 120 covers the reaction block 110. When the showerhead plate 120 is rotated and separated from the reaction block 110, thefirst and second connection pipes 111 and 112 are separated from thefirst and second connection lines 121 and 122.

[0026] At least two exhaust holes 117 and 118 for exhausting introducedinert gases and/or reaction gases are formed to be symmetrical to eachother on the bottom of the reactor block 110. A main O-ring 114 isinstalled on the upper surface of the reactor block 110, so that thereactor block 110 and the shower head plate 120 are securely sealed whenthe shower head plate 120 is covered.

[0027] The shower head plate 120 covers the reactor block 110, so that apredetermined pressure is constantly maintained within the reactor block110. Also, the shower head plate 120 covers the reactor block 110 sothat the diffusion plate 130 is placed within the reactor block 110.

[0028] The diffusion plate 130, which sprays a gas during a thin filmdeposition process, has a plurality of spray holes 131, which areconnected to the first connection line 121, and spray a first reactiongas and/or inert gas onto the wafer w, and a plurality of nozzles 133,which are connected to a passage 132 leading to the second connectionline 122 and face the inner side surface of the reactor block 110 tospray a second reaction gas and/or inert gas onto the edges of the waferw.

[0029] A first mixing portion 134 for evenly mixing a first reaction gasand an inert gas and flowing the mixture to the spraying hole 131 isformed at the center of the inside of the diffusion plate 130, as shownin FIGS. 4 and 5. The first reaction gas and the inert gas flowing viathe connection line 121 are swirled and mixed, and then diffused andevenly sprayed onto the wafer via all of the spray holes 131.

[0030] Spray holes 131 are not formed below the first mixing portion 134in the diffusion plate 130, as shown in FIGS. 3 and 5. Preferably, theentire area of the diffusion plate 130 having the spray holes 131 islarger than the area of the wafer w, so that a gas can be evenly spayedover the entire surface of the wafer.

[0031] Preferably, the diameter of the spray holes 131 is between 1 mmand 2.5 mm. This diameter, which is obtained by several experiments,allows an excellent thin film to be formed on the wafer w. Also, thenumber of spray holes 131 is about 100 to 1000 according to theirdiameter. In this embodiment, more than 160 spray holes are formed. Thecross-section of the diffusion plate 130 between spray holes 131 has theshape of upside-down T, so that thermal energy from the wafer block 140is smoothly transmitted to the shower head plate 120 in order to preventthe diffusion plate 130 from being overheated.

[0032] The nozzles 133 lead to the passages 132 radially formed from asecond mixing portion 135, and are slanted toward the inner side surfaceof the reactor block 110, as shown in FIG. 4. Preferably, there are30-100 nozzles 133. In the present embodiment, 48 nozzles are formed.

[0033] The second mixing portion 135 for evenly mixing a second reactiongas and an inert gas is formed between the second connection line 122and the shower head plate 120, as shown in FIG. 4. The second mixingportion 135 has a structure in which a hole 135 b is formed through apartition 135 a.

[0034] The wafer block 140, on which the wafer w is to be seated, isinstalled within the reactor block 110. A heater H is installed in thewafer block 140 to heat and maintain the wafer block 140 to apredetermined temperature during deposition.

[0035] The interval (D) between the diffusion plate 130 and the waferblock 140 is in the range of 20 mm to 50 mm. Referring to FIG. 6, whichis a graph showing the interval (D) and specific resistance duringdeposition of a thin film, it can be seen that the specific resistanceis the lowest when the interval (D) between the diffusion plate 130 andthe wafer block 140 is 30 mm. However, when other conditions, forexample, the types and amounts of first and second reaction gases, thetemperature of a wafer block, or the like, were changed, specificresistance values were low at the intervals D within a range of about 20to 50 mm, and it can be concluded that the interval D is an importantstructural property in forming an excellent thin film.

[0036] The interval within this range is compared to a conventionalchemical vapor deposition (CVD) reactor in which the interval between adiffraction plate to which a reaction gas is sprayed and a wafer blockon which a wafer is seated is about 50 to 100 mm. In the presentinvention, since the interval D is smaller than that in the prior art, adense first reaction gas layer is formed on a wafer w by the pressure ofa first reaction gas and/or inert gas sprayed from the spraying holes131. The first reaction gas layer reacts with a second reaction gasflowed in later, so that a thin film having a higher purity and anexcellent electrical property can be formed.

[0037] A pumping baffle 150 is installed around the wafer block 140. Thepumping baffle 150 is made up of a sidewall 150 a installed on thelateral side of the wafer block 140, and a bottom wall 150 b throughwhich symmetrical holes 150 c are formed. A donut-shaped pumping pot 115connected to an exhaust line is formed below the bottom wall 150 b ofthe pumping baffle 150, that is, on the bottom of the reactor block 110.

[0038] The sidewall 150 a and the bottom wall 150 b of the pumpingbaffle 150 provide a space in which a second reaction gas and/or inertgas sprayed onto the inner side surface of the reactor block 110 canmore evenly react to the first reaction gas layer formed on the wafer w.A process product generated during deposition of a thin film, and gasesnot used during deposition of a thin film are slipped through the hole150 c. These gases pass through the exhaust holes 117 and 118, and areexhausted via the pumping pot 115.

[0039] When a thin film is deposited, the pressure within a reactor mustbe maintained to be 1 to 10 torr. In order to observe and control thispressure, a pressure measuring portion 160 must be installed within thereactor.

[0040] The reactor 100 has heaters (H) formed inside and outside to heatthe reactor when a thin film is deposited. In this embodiment, when aTiN thin film is deposited, the temperature of the inner surface of thereactor block 110 must be kept at about 120 to 200° C., and thetemperature of the diffusion plate 130 must be kept at about 150 to 260°C. Also, the wafer block 140 must be kept at a temperature of about 425to 650° C., and the pumping baffle 150 must be kept at a temperature ofabout 150 to 230° C. The temperature of a vat valve 101 between thereactor 100 and a transfer module 102 for supplying and transferring awafer w must be maintained at about 140 to 170° C.

[0041] In the reactor 100, in a state where the wafer w transferred viathe wafer transfer hole 116 is seated on the wafer block 140 and heatedto a predetermined temperature, a first reaction gas and/or inert gas issprayed onto the wafer w through the spray holes 131 of the diffusionplate 130 along a route from the first connection pipe 111 to the firstconnection line 121, and a second reaction gas and/or inert gas issprayed onto the edges of the wafer w through the nozzles 133 along aroute from the second connection pipe 112, to the second connection line122, and to the passage 132. The first and second reaction gases areused to form a thin film on the wafer w, and process products or gasesnot used for depositing a thin film are exhausted to the outside throughthe exhaust holes 117 and 118 and the pumping pot 115.

[0042] As shown in FIG. 1, the gas jungle includes a first reaction gassupply portion 210 for supplying a reaction gas to the reactor 100, anda second reaction gas supply portion 230 for supplying a second gas tothe reaction gas 100.

[0043] The first reaction gas supply portion 210 is connected to thereactor 100 via a first reaction gas supply line 220, and the secondreaction gas supply portion 230 is connected to the reactor 100 via asecond reaction gas supply line 240.

[0044] A first inert gas supply line 260 through which an inert gassupplied from the inert gas supply source 250 flows is connected to thefirst reaction gas supply line 220, and a second inert gas supply line270 through which an inert gas supplied from the inert gas supply source250 flows is connected to the second reaction gas supply line 240.

[0045] The first reaction gas supply portion 210 includes a bubbler 211for gasifying a first reaction material, a first reaction gas mass flowcontroller (MFC) 212 for controlling the flow of a first reaction gassupplied from the bubbler 211, and first and second valves V1 and V2installed on the line between the bubbler 211 and the first reaction gasMFC 212 for allowing or blocking the flow of a first reaction gas.

[0046] A third valve V3 for allowing or blocking the flow of the firstreaction gas controlled by the first reaction gas MFC 212 is installedon the first reaction gas supply line 220.

[0047] The second reaction gas supply portion 230 includes a fourthvalve V4 for allowing or blocking the flow of a second reaction gas, anda second reaction gas MFC 232 for controlling the flow of a secondreaction gas passed through the fourth valve V4. A fifth valve V5 forallowing or blocking the flow of a second reaction gas controlled by thesecond reaction gas MFC 232 is installed on the second reaction gassupply line 240.

[0048] A sixth valve V6 for allowing or blocking the flow of a suppliedinert gas, a first inert gas MFC 262 for controlling the flow of aninert gas passed through the sixth valve V6, and a seventh valve V7 forallowing or blocking the flow of an inert gas controlled by the firstinert gas MFC 262, are installed on the first inert gas supply line 260.

[0049] An eighth valve V8 for allowing or blocking the flow of asupplied inert gas, a second inert gas MFC 272 for controlling the flowof an inert gas passed through the eighth valve V8, and a ninth valve V9for allowing or blocking the flow of an inert gas controlled by thesecond inert gas MFC 272, are installed on the second inert gas supplyline 270.

[0050] Here, the gas jungle includes a first bypass line 280 forallowing a first reaction gas and/or inert gas to flow directly to theexhaust line 400 without passing through the reactor 100, and a secondbypass line 290 for allowing a second reaction gas and/or inert gas toflow directly to the exhaust line 400 without passing through thereactor 100.

[0051] The first bypass line 280 has a tenth valve V10 connected to theline between the first reaction gas MFC 212 and the third valve V3 forallowing or blocking the flow of a first reaction gas to the exhaustline 400, and an eleventh valve V11 connected to the line between thefirst inert gas MFC 262 and the seventh valve V7 for allowing orblocking the flow of an inert gas to the exhaust line 400.

[0052] The second bypass line 290 has a twelfth valve V12 connected tothe line between the second reaction gas MFC 232 and the fifth valve V5for allowing or blocking the flow of a second reaction gas to theexhaust line 400, and a thirteenth valve V13 connected to the linebetween the second inert gas MFC 272 and the ninth valve V9 for allowingor blocking the flow of an inert gas to the exhaust line 400.

[0053] The first and second bypass lines 280 and 290 are adopted topurge the lines within the gas jungle, when a small amount of gas flowedin while a material of a first or second reaction gas or an inert gas isexchanged must flow directly to the exhaust line 400 without passing bythe reactor 100, when a contaminating source is generated within thelines, or when a new gas jungle is replaced.

[0054] As described above, first and second reaction gases, air orcontaminating sources remaining within lines are purged directly to theexhaust line 400 via the first and second bypass lines 280 and 290 by aninert gas, so that the reactor 100 can be prevented from beingcontaminated. Thus, the first and second bypass lines 280 and 290 arenot used in processes for depositing a thin film, but used only inspecific cases.

[0055] The gas jungle further includes a separate inert gas supply line320 for supplying an inert gas from the inert gas supply source 310 inorder to purge gases and/or contaminating sources remaining in thelines. The inert gas supply line 320 is organically connected to thefirst and second reaction gas supply portions 210 and 230, the first andsecond inert gas supply lines 260 and 270, the first and second bypasslines 280 and 290, and the exhaust line 400. The inert gas supply line320 is connected to gas lines fundamentally required by a process, via afourteenth valve V14 for allowing or blocking the flow of an inert gasto the first reaction gas supply portion 210, a fifteenth valve V15 forallowing or blocking the flow of an inert gas to the second reaction gassupply portion 230, a sixteenth valve V16 for allowing or blocking theflow of an inert gas to the first inert gas supply line 260, aseventeenth valve V17 for allowing or blocking the flow of an inert gasto the second inert gas supply line 270, an eighteenth valve V18 forallowing or blocking the flow of an inert gas to the first bypass line280, and a nineteenth valve V19 for allowing or blocking the flow of aninert gas to the second bypass line 290.

[0056] The gas jungle further includes a cleaning gas supply line 340connected to at least one of the first and second reaction gas supplylines 220 and 240, in order to clean the reactor 100. In thisembodiment, the cleaning gas supply line 340 allows a cleaning gas fromthe cleaning gas supply portion 330 to flow to the reactor 100 via thefirst reaction gas supply line 220.

[0057] The cleaning gas supply line 340 includes a twenty-first valveV21 for allowing or blocking the flow of a supplied cleaning gas, acleaning gas MFC 342 for controlling the flow of a cleaning gas passedthrough the twenty-first valve V21, and a twenty-second valve V22 forallowing or blocking the flow of a cleaning gas controlled by thecleaning gas MFC 342.

[0058] The reactor 100, the first and second bypass lines 280 and 290and the cleaning gas supply line 340 are connected to the exhaust line400. A throttle valve TV controlled by the internal pressure of thereactor 100 measured by the pressure measuring portion 160, forcontrolling the amount of an exhausted gas, is installed on the exhaustline 400. Twenty-third, twenty-fourth and twenty-fifth valves V23, V24and V25 for allowing or blocking the flow of an exhausted gas are alsoinstalled on the exhaust line 400. Here, the first bypass line 280 isconnected to the line between the twenty-third and twenty-fourth valvesV23 and V24, and the second bypass line 290 is connected to the linebetween the twenty-fifth valve V25 and the exhaust pump 410.

[0059] In this gas jungle, a cold spot due to undesired condensationoccurring when a reaction gas flows may be formed. Since a cold spotbadly affects the process for depositing a thin film, heaters (notshown) for preventing generation of a cold spot are installed on thelines. Preferably, the heaters are independently installed at as manyareas as possible along lines, and a temperature gradient is formedalong each line. In this embodiment, the temperature gradient isestablished to be within a range of 40 to 200° C. toward the reactor100.

[0060] In the operation of the first embodiment of an ALD thin filmdeposition apparatus having such a structure, TiCl₄ is used as a firstreaction gas, NH₃ is used as a second reaction gas, and Ar is used as aninert gas. Thus, liquid TiCl₄ is contained in the bubbler 211.

[0061] The reactor 100 is combined with a transfer module 102 forsupplying and transferring a wafer w, via a vat valve 101, as shown inFIG. 7. The wafer w is transferred into the reactor 100 via a wafertransfer hole 116 using a robot arm (not shown) of the transfer module102, and seated on the wafer block 140.

[0062] When the wafer w is seated on the wafer block 140, thetemperature of the wafer block 140 increases within a range of 425 to650° C., so that the temperature of the wafer w is increased to 400 to600° C. After the wafer temperature is stabilized, the step ofintroducing a gas into the reactor 100 is performed.

[0063] The gas introducing step starts by opening the first valve V1,the sixth valve V6, the eighth valve V8, and the fourth valve V4 forseveral seconds. Then, a bubbled TiCl₄ gas is filled up to the secondvalve V2, and Ar gas is filled up to the seventh and ninth valves V7 andV9 after its amount is appropriately controlled by the first and secondinert gas MFCs 262 and 272. An NH3 gas is filled up to the fifth valveV5 after its amount is appropriately controlled by the second reactiongas MFC 232.

[0064] Next, an inert gas is flowed into the reactor 100 through theseventh and ninth valves V7 and V9. Before a gas is introduced, theinternal pressure of the reactor 100 is kept at 10⁻⁴˜5×10⁻³ torr.However, as an inert gas is introduced, the internal pressure of thereactor 100 is 1 to 10 torr. This pressure is obtained by the pressuremeasuring portion 160 installed in the reactor 100 appropriately openingthe throttle valve TV of the exhaust line 400. Here, the reason why theseventh and ninth valves V7 and V9 are opened after the sixth and eighthvalves V6 and V8 are opened is that the gas within the reactor 100 mayflow backward through the seventh and ninth valves V7 and V9 when theyare suddenly opened.

[0065] The gas introducing step is followed by a step of preventingparticles from being generated during deposition of a thin film.Particles produced during deposition of a thin film deteriorate thequality of a thin film, so the particle generation preventing step isvery important. This step is performed by opening the fifth valve V5 atleast several seconds before a TiCl₄ gas is flowed into the reactor 100,while an Ar gas is continuously flowed into the reactor 100, andintroducing an NH₃ gas into the reactor 100.

[0066] If a TiCl₄ gas is introduced into the reactor 100 before an NH₃gas is introduced, part of the TiCl₄ gas reacts to the surface of thediffusion plate 130, which generates particles as byproducts. At thistime, the particle generation preventing step is performed as describedabove. Particles may be very fine particles of a TiNxCly layer depositedon the diffusion plate 130 or the material Al of the diffusion plate.Accordingly, in order to prevent particles from being generated from thesurface of the diffusion plate 130, an NH₃ gas is introduced severalseconds before an TiCl₄ gas is introduced, so that an NH₃ layer isformed on the surface of the diffusion plate 130. The NH₃ layer on thediffusion plate 130 reacts to a TiCl₄ gas which is introduced duringreal deposition of a thin film, and the TiCl₄ gas is prevented fromgenerating particles from the surface of the diffusion plate 130.

[0067] The generation of fine particles is prevented by the principlethat a TiCl₄ gas reacts to an NH₃ layer previously formed on thediffusion plate 130 and thus changes to an HCl vapor to be describedlater, so that the TiCl₄ gas is prevented from reacting to the surfaceof the diffusion plate 130 or instantaneously etching the same. Thevapor byproducts are immediately exhausted via the exhaust line 400 tothe outside. A series of reactions occurring within the reactor 110 maybe expressed as in the following chemical formula:2NH3+TiCl4→TiN(s)+4HCl(g)+H2(g)+0.5N2(g).

[0068] After the particle generation preventing step, a TiN thin film isreally deposited on a wafer w by controlling the flow of a TiCl₄ gas andan NH₃ gas into the reactor 100.

[0069] Deposition of a thin film is performed by alternately introducinga TiCl₄ gas and an NH₃ gas into the reactor 100. It doesn't matter whichgas is introduced first. For example, when a TiCl₄ gas is introducedfirst, a TiCl₄ gas and an Ar gas are first introduced into the reactor,in the first step. After a predetermined period of time, the TiCl₄ gasis excluded. Thus, a TiCl₄ layer is formed on the wafer w, andcompressed by an Ar gas which is continuously introduced.

[0070] In the second step, an NH₃ gas and an Ar gas are introducedtogether. The supply of the NH₃ gas is blocked for a predeterminedperiod of time. The NH₃ gas reacts to the TiCl₄ layer previously formedon the wafer w, thereby forming a TiN thin film on the wafer w. That is,a TiN+NH₃ layer is formed by the consecutive first and second steps.

[0071] Next, the first step is again performed to continuously grow athin film on the TiN+NH₃ layer. Then, the TiN+NH₃ layer is changed to aTiN+TiN+TiCl₄ layer. Thereafter, the second step is performed to form aTiN+TiN+TiN+NH₃ layer. A TiN thin film having a desired thickness can beobtained by repeating this process.

[0072] This TiN thin film deposition process is performed by alternatelyopening and closing the third and fifth valves V3 and V5 in a statewhere the first and fourth valves V1 and V4 are always open, while an Argas is continuously introduced into the reactor 100 by opening thesixth, seventh, eighth and ninth valves V6, V7, V8 and V9.

[0073] Here, the second valve V2 is opened before the third valve V3, sothat a TiCl₄ gas passes through the first reaction gas MFC 212 and isfilled up to the third valve V3. Thereafter, when the third valve V3 isopened to send a first reaction gas to the reactor 100, the second valveV2 is closed. That is, a first reaction gas passes through the firstreaction gas supply line 220 in units of valves. A process byproduct gasgenerated during reaction is exhausted via the throttle valve TV of theexhaust line 400, and the twenty-third, twenty-fourth and twenty-fifthvalves V23, V24 and V25.

[0074] To sum up the above-described reaction, a TiCl₄ gas flows to thefirst reaction gas supply line 220 via the third valve V3 after its flowis controlled by the first and second valves V1 and V2, and an Ar gas iscontrolled in its flow, passes through the seventh valve V7, is mixedwith the TiCl₄ gas on the first reaction gas supply line 220, and flowsto the reactor 100.

[0075] Thereafter, a mixture of TiCl₄ and Ar pass through the firstconnection pipe 111 and the first connection line 121, is evenly mixedonce more in the first mixing portion 134, and is evenly sprayed overthe wafer w through the spray holes 131. An NH₃ reaction gas iscontrolled in its flow through the fourth valve V4, and then flows tothe second reaction gas supply line 240 via the fifth valve V5. An Argas is controlled in its flow, passes through the ninth valve V9, ismixed with an NH₃ gas on the second reaction gas supply line 240, andthen flows to the reactor 100. Next, a mixture of NH₃ and Ar passthrough the second connection pipe 112 and the second connection line122, is evenly mixed once more in the second mixing portion 135, and issprayed toward the inner sidewall of the reactor block 110 through thenozzles 133.

[0076] Here, it is preferable that the flow of a TiCl₄ gas is 1 SCCM ormore, the flow of an Ar gas to be mixed with a TiCl₄ gas is 50 SCCM ormore, the flow of NH₃ is 50 SCCM or more, and the flow of an Ar gas tobe mixed with an NH₃ gas is 60 SCCM or more. These values are obtainedby several experiments. When the flow rates are at least as describedabove, a thin film having a high purity, an excellent electricalproperty, and a good step coverage can be obtained.

[0077] In this embodiment, an NH₃ gas is introduced at least one secondafter a TiCl₄ gas is excluded.

[0078] Also, a duration when a TiCl₄ gas and an inert gas are introducedinto the reactor 100, and a duration when the TiCl₄ gas is excludedbefore an NH₃ gas is flowed into the reactor 100, are at a ratio of 1 to1.2 or greater.

[0079] The ratio of the flow of an inert gas introduced via the firstinert gas supply line 260 to the flow of an inert gas introduced via thesecond inert gas supply line 270 is set to be 1 to 1.2 or greater, inorder to prevent a strongly-diffusible TiCl₄ gas from flowing backwardvia the second reaction gas supply line 240.

[0080] This thin film deposition is achieved by consecutive gas sprayingto the reactor 100, and the process pressure of the reactor ismaintained constant by an appropriate signal exchange and controlbetween a pressure measuring portion and valves including a throttlevalve. Therefore, the uniformity of a deposited thin film is improved.

[0081] While a TiN thin film is deposited on a wafer, Cl can becontained in the thin film. Since Cl deteriorates the purity andelectrical characteristics of a thin film, a Cl removing step is alsoimportant. The Cl removing step is performed by closing the third valveV3 to prevent introduction of a TiCl₄ gas, and opening the sixth andseventh valves V6 and V7, the eighth and ninth valves V8 and V9, and thefourth and fifth valves V4 and V5. That is, only an Ar gas and an NH₃gas are supplied to the reactor 100. Then, an NH₃ gas reacts to Clwithin the TiN thin film formed on the wafer, thereby producing an HCl.The HCl is exhausted to the outside. This Cl removing step can beomitted when the content of Cl in a thin film is sufficiently low.

[0082] Even when a compound gas containing Ta is used as a firstreaction gas, and a compound gas containing N, for example, an NH₃ gas,is used as a second reaction gas, a TaN thin film can be deposited on awafer by the method described above.

[0083] A second embodiment of an ALD thin film deposition apparatusaccording to the present invention will now be described with referenceto FIG. 8. The same reference numerals as those in FIG. 1 denote thesame elements.

[0084] In contrast to the first embodiment in which a TiN or TaN thinfilm can be deposited on a wafer, a thin film such as a WN thin film canbe formed in the second embodiment. In order to achieve the secondembodiment, the first reaction gas supply portion 210 in the firstembodiment is replaced with a first reaction gas supply portion 510. Thefirst reaction gas supply portion 510 includes a thirty-first valve V31of allowing or blocking the flow of a first reaction gas, and a firstreaction gas MFC 512 for controlling the flow of a first reaction gaswhich has passed through the thirty-first valve V31. The first reactiongas supply portion 510 is connected to the third valve V3. WF6 is usedas the material of a first reaction gas, a compound gas containing N,for example, an NH₃ gas, is used as a second reaction gas, and an Ar gasis used as an inert gas.

[0085] Deposition of a WN thin film is performed by alternatelyintroducing an NH₃ gas and a WF₆ gas into the reactor 100. For example,when a WF6 gas is first introduced, an Ar gas is introduced together,and the WF6 gas is excluded for a predetermined period of time, in thefirst step. Then, a WF6 layer is formed on the wafer, and is compressedby an Ar gas which is continuously introduced. In the second step, anNH₃ gas and an Ar gas are introduced together, and the flow of an NH₃gas is stopped for a predetermined period of time. The NH₃ gas reacts tothe WF6 layer formed on the wafer, thereby forming a WN thin film on thewafer. That is, a WN+NH₃ layer is formed by consecutive first and secondsteps.

[0086] Next, the first step is again performed to continuously grow athin film on the WN+NH₃ layer. Then, the WN+NH₃ layer is changed to aWN+WN+WF6 layer. Thereafter, the second step is performed to form aWN+WN+WN+NH₃ layer. Therefore, a WN thin film having a desired thicknesscan be obtained by repeating this process.

[0087] A third embodiment of an ALD thin film deposition apparatusaccording to the present invention will now be described with referenceto FIG. 9. The same reference numerals as those in FIG. 1 denote thesame elements.

[0088] In contrast to the first embodiment in which a TiN or TaN thinfilm can be deposited on a wafer, a thin film such as a Ti or TiAlN filmas well as a TiN or TaN film can be formed in the third embodiment. Inorder to achieve this, the third embodiment further includes a thirdreaction gas supply portion 620 for supplying a third reaction gasTriMethylAluminum (TMA) to the second reaction gas supply line 240, anda fourth reaction gas supply portion 610 for supplying a fourth reactiongas H2 to the second reaction gas supply line 240.

[0089] The fourth reaction gas supply portion 610 includes a thirtysecond valve V32 for allowing or blocking the flow of supplied H2, afourth reaction gas MFC 612 for controlling the flow of H2 which haspassed through the thirty second valve V32, and a thirty third valve V33for allowing or blocking the flow of H2 controlled by the fourthreaction gas MFC 612.

[0090] The third reaction gas supply portion 620 includes a bubbler 621for gasifying a third reaction material, a third reaction gas MFC 622for controlling the flow of a third reaction gas, a thirty fourth valveV34 installed on the line between the bubbler 621 and the third reactiongas MFC 622 for allowing or blocking the flow of the third reaction gas,and a thirty fifth valve V35 for allowing or blocking the flow of thethird reaction gas, which has been controlled by the third reaction gasMFC 622, to the second reaction gas supply line 240.

[0091] That is, in this structure, a compound gas containing a transfermetal element Ti or Ta is used as a first reaction gas, an Ar gas isused as an inert gas, a TMA gas is used as a third reaction gas, and anH2 gas is used as a fourth reaction gas.

[0092] The third embodiment of the thin film deposition apparatus havingsuch a configuration is almost the same as the first embodiment, so itwill not be described in detail.

[0093] In all of the embodiments described above, a TiCl₄ gas or acompound gas containing a transfer metal element such as Ti, Ta or W isused as a first reaction gas. However, other gases can be used as thefirst reaction gas. Other gases such as He or N₂ instead of Ar gas canbe used as an inert gas. Also, other compound gases including N, insteadof an NH₃ gas, can be used as a second reaction gas.

[0094] In the first, second and third embodiments of an ALD thin filmdeposition apparatus according to the present invention, as to first andsecond reaction gases that have a major role in a thin film depositionprocess, a mixture of a first reaction gas an inert gas is sprayed ontoa wafer, and a mixture of an NH₃ gas and an inert gas is sprayed towardthe inner sidewall of a reactor block. The interval between a diffusionplate and a wafer block is narrowed to about 20 to 50 mm, so thatseveral reaction gases react to each other while being sequentiallycompressed down on the wafer. Therefore, a Ti, TiAlN, TiN, TaN or WNfilm having high purity, excellent electrical characteristics, and agood step coverage can be deposited.

[0095] Also, an NH3 gas is sprayed to a reactor several seconds before afirst reaction gas is sprayed thereto, so that generation of particlescan be prevented.

[0096] Furthermore, an NH3 gas is sprayed to a reactor 100 afterdeposition of a thin film is completed, or during deposition, so that Clexisting within the thin film can be removed. Thus, the electricalcharacteristics of the thin film can be improved.

What is claimed is:
 1. An atomic layer deposition (ALD) thin filmdeposition apparatus comprising: a reactor 100 in which a wafer ismounted and a thin film is deposited on the wafer; a first reaction gassupply portion 210 for supplying a first reaction gas to the reactor100; a second reaction gas supply portion 230 for supplying a secondreaction gas to the reactor 100; a first reaction gas supply line 220for connecting the first reaction gas supply portion 210 to the reactor100; a second reaction gas supply line 240 for connecting the secondreaction gas supply portion 230 to the reactor 100; a first inert gassupply line 260 for supplying an inert gas from an inert gas supplysource 250 to the first reaction gas supply line 220; a second inert gassupply line 270 for supplying an inert gas from the inert gas supplysource 250 to the second reaction gas supply line 240; and an exhaustline 400 for exhausting the gas within the rector 100 to the outside. 2.The ALD thin film deposition apparatus of claim 1, wherein the firstreaction gas supply portion 210 comprises: a bubbler 211 for gasifying afirst reaction material; a first reaction gas mass flow controller (MFC)212 for controlling the flow of a first reaction gas supplied from thebubbler 211; and a first valve V1 installed on the line between thebubbler 211 and the first reaction gas MFC 212 for allowing or blockingthe flow of the first reaction gas.
 3. The ALD thin film depositionapparatus of claim 2, further comprising a third valve V3 installed onthe first reaction gas supply line 220 for allowing or blocking the flowof the first reaction gas controlled by the first reaction gas MFC 212.4. The ALD thin film deposition apparatus of claim 1, wherein the secondreaction gas supply portion 230 comprises: a fourth valve V4 forallowing or blocking the flow of the second reaction gas; and a secondreaction gas MFC 232 for controlling the flow of a second reaction gaswhich has passed through the fourth valve V4.
 5. The ALD thin filmdeposition apparatus of claim 4, further comprising a fifth valve V5installed on the second reaction gas supply line 240 for allowing orblocking the flow of the second reaction gas controlled by the secondreaction gas MFC
 232. 6. The ALD thin film deposition apparatus of claim1, wherein a sixth valve V6 for allowing or blocking the flow of asupplied inert gas, a first inert gas MFC 262 for controlling the flowof an inert gas which has passed through the sixth valve V6, and aseventh valve V7 for allowing or blocking the flow of an inert gas whichhas been controlled by the first inert gas MFC 262, are formed on thefirst inert gas supply line
 260. 7. The ALD thin film depositionapparatus of claim 1, wherein an eighth valve V8 for allowing orblocking the flow of a supplied inert gas, a second inert gas MFC 272for controlling the flow of an inert gas which has passed through theeighth valve V8, and a ninth valve V9 for allowing or blocking the flowof an inert gas which has been controlled by the second inert gas MFC272, are formed on the second inert gas supply line
 270. 8. The ALD thinfilm deposition apparatus of claim 1, further comprising: a first bypassline 280 for allowing the first reaction gas and/or inert gas to flowdirectly to the exhaust line 400 without passing through the reactor100, the first bypass line having a tenth valve V10 for allowing orblocking the flow of the first reaction gas to the exhaust line 400 andan eleventh valve V11 for allowing or blocking the flow of the inert gasto the exhaust line 400; and a second bypass line 290 for allowing thesecond reaction gas and/or inert gas to flow directly to the exhaustline 400 without passing through the reactor 100, the second bypass linehaving a twelfth valve V12 for allowing or blocking the flow of thesecond reaction gas to the exhaust line 400 and a thirteenth valve V13for allowing or blocking the flow of the inert gas to the exhaust line400.
 9. The ALD thin film deposition apparatus of claim 1, furthercomprising a separate inert gas supply line 320 for purging andexhausting the gas and/or contaminating sources existing within lines,the inert gas supply line 320 organically connected to the first andsecond reaction gas supply portions 210 and 230, the first and secondinert gas supply lines 260 and 270, the first and second bypass lines280 and 290, and the exhaust line
 400. 10. The ALD thin film depositionapparatus of claim 1, wherein the first reaction gas is a TiCl₄ gas or acompound gas containing Ta, and the second reaction gas is NH₃.
 11. TheALD thin film deposition apparatus of claim 1, wherein a first reactiongas supply portion 510 comprises: a thirty first valve V31 for allowingor blocking the flow of a first reaction gas; and a first reaction gasMFC 512 for controlling the flow of a second reaction gas which haspassed through the thirty first valve V31.
 12. The ALD thin filmdeposition apparatus of claim 11, wherein the first reaction gas is WF₆,and the second reaction gas is NH₃.
 13. The ALD thin film depositionapparatus of claim 1, further comprising: a third reaction supplyportion 620 for supplying a third reaction gas to the second reactiongas supply line 240; and a fourth reaction supply portion 610 forsupplying a fourth reaction gas to the second reaction gas supply line240, wherein the fourth reaction gas supply portion 610 has a thirtysecond valve V32 for allowing or blocking the flow of a fourth reactiongas, a fourth reaction gas MFC 612 for controlling the flow of a fourthgas which has passed through the thirty second valve V32, and a thirtythird valve V33 for allowing or blocking the flow of a fourth gas whichhas been controlled by the fourth reaction gas MFC
 612. 14. The ALD thinfilm deposition apparatus of claim 13, wherein the third reaction gassupply portion 620 comprises: a bubbler 621 for gasifying a thirdreaction material; a third reaction gas MFC 622 for controlling the flowof the third reaction gas supplied from the bubbler 621; a thirty fourthvalve V34 installed on the line between the bubbler 621 and the thirdreaction gas MFC 622 for allowing or blocking the flow of the thirdreaction gas; and a thirty fifth valve V35 for allowing or blocking theflow of the third reaction gas, which has been controlled by the thirdreaction gas MFC 622, to the second reaction gas supply line
 240. 15.The ALD thin film deposition apparatus of claim 14, wherein the firstreaction gas is a compound gas containing a transfer metal element suchas Ti, Ta or W, and the second reaction gas is NH₃.
 16. The ALD thinfilm deposition apparatus of claim 14, wherein the third reaction gas isTriMethylAluminum (TMA), and the fourth reaction gas is H₂.
 17. An ALDthin film deposition method using a thin film deposition apparatusincluding a reactor 100 in which a wafer is mounted and a thin film isdeposited on the wafer, a first reaction gas supply portion 210 forsupplying a first reaction gas to the reactor 100, a first reaction gassupply line 220 for connecting the first reaction gas supply portion 210to the reactor 100, a second reaction gas supply portion 230 forsupplying a second reaction gas to the reactor 100, a second reactiongas supply line 240 for connecting the second reaction gas supplyportion 230 to the reactor 100, a first inert gas supply line 260 forsupplying an inert gas, the flow of which has been controlled, to thefirst reaction gas supply line 220, a second inert gas supply line 270for supplying an inert gas, the flow of which has been controlled, tothe second reaction gas supply line 240, and an exhaust line 400 forexhausting the gas within the rector 100 to the outside, wherein a firstreaction gas, the flow of which has been controlled, and theflow-controlled inert gas are mixed and supplied to the upper surface ofthe wafer within the reactor 100, and a second reaction gas, the flow ofwhich has been controlled, and the flow-controlled inert gas are mixedand supplied to the edges of the wafer within the reactor
 100. 18. Themethod of claim 17, further comprising a particle generation preventingstep of introducing the NH₃ gas into the reactor 100 several secondsbefore the first reaction gas in the initial state is introduced intothe reactor 100, in order to prevent particles from being producedduring deposition of a thin film, when a compound gas containing Cl isused as the first reaction gas, and an NH₃ gas is used as the secondreaction gas.
 19. The method of claim 17, wherein a first step of mixingthe first reaction gas and the inert gas and introducing the mixtureinto the reactor 100 and excluding the first reaction gas for apredetermined period of time, and a second step of introducing thesecond reaction gas and the inert gas into the reactor 100 and excludingthe second reaction gas for a predetermined period of time, arerepeated.
 20. The method of claim 19, wherein, when a compound gascontaining a transfer metal element such as Ti, Ta or W is used as thefirst reaction gas, and an NH₃ gas is used as the second reaction gas,the temperature of the wafer during thin film deposition is maintainedat 400 to 600° C., and the temperature of lines connected to the reactoris maintained at 40 to 200° C.
 21. The method of claim 20, wherein theflow rate of the first reaction gas is controlled to 1 SCCM or higher,the flow rate of an inert gas mixed with the first reaction gas iscontrolled to 50 SCCM or higher, the flow rate of an NH₃ gas iscontrolled to 50 SCCM or higher, and the flow rate of an inert gas mixedwith the NH₃ gas is controlled to 60 SCCM or higher.
 22. The method ofclaim 17, further comprising a step of introducing only the inert gasand the NH₃ gas to the reactor 100 to remove Cl from a thin filmdeposited on the wafer, when a compound gas containing Cl is used as thefirst reaction gas.
 23. The method of claim 21, wherein, when the firstand second reaction gases and/or inert gas is introduced into thereactor 100, the inside pressure of the reactor 100 is 1 to 10 torr. 24.The method of claim 19, wherein, when a TiCl₄ gas is used as the firstreaction gas, and an NH₃ gas is used as the second reaction gas, the NH₃gas is introduced at least one second after the TiCl₄ gas is excluded.25. The method of claim 24, wherein a duration when the TiCl₄ gas andthe inert gas are introduced into the reactor 100, and a duration whenthe TiCl₄ gas is excluded before an NH₃ gas is flowed into the reactor100, are at a ratio of 1 to 1.2 or greater.
 26. The method of claim 25,wherein the ratio of the flow of an inert gas introduced via the firstinert gas supply line 260 to the flow of an inert gas introduced via thesecond inert gas supply line 270 is set to be 1 to 1.2 or greater, inorder to prevent the strongly-diffusible TiCl₄ gas from flowing backwardvia the second reaction gas supply line
 240. 27. The method of claim 17,wherein, when the first reaction gas supply portion 210 includes abubbler 211 for gasifying a first reaction material, a first reactiongas MFC 212 for controlling the flow of a flowing first reaction gas,and first and second valves V1 and V2 installed on the line between thebubbler 211 and the first reaction gas MFC 212 for allowing or blockingthe flow of a first reaction gas, and the first reaction gas supply line220 includes a third valve V3 for allowing or blocking the flow of afirst reaction gas controlled by the first reaction gas MFC 212, thefirst reaction gas is passed through the first reaction gas MFC 212 byopening the first and second valves V1 and V2, and fills the third valveV3 for a predetermined period of time, and then the second valve V2 isclosed when the first reaction gas is sent to the reactor 100 by openingthe third valve V3.